A vehicle having an internal combustion engine includes a fuel tank that stores liquid fuel such as gasoline, diesel, methanol or other fuels. The liquid fuel evaporates into fuel vapors that increase pressure within the fuel tank. Evaporation is caused by energy that is transferred to the fuel tank. Sources of energy include radiation (e.g. sun energy), convection and conduction. Increased vapor pressure in the fuel system may effect the rate that vapor fuel is released into the atmosphere through a leak in the fuel system. Vapor leak diagnostic systems attempt to diagnose vapor fuel leaks.
Typically, vapor leak detection systems abort when a sudden pressure spike is detected. In some cases, a sudden pressure change can be indicative of a refueling event and an abort of the vapor leak detection algorithm is proper. However, in other cases, an event such as a trunk slam, door slam or vehicle rocking can cause a rapid pressure change in the fuel tank. In such cases, aborting the leak detection test reduces the robustness of the test and increases the time it takes to detect a leak.